Your question: Why is the speed of DC shunt motor dependent on back EMF *?

For d.c. shunt motor the speed is dependent on induced e.m.f. only because. Flux is proportional to armature current. Flux is practically constant in d.c. Armature drop is negligible.

Why is the speed of DC shunt motor depend on the back emf?

In the case of DC motors Speed ∝ Back emf(Eb)/flux(φ). The field winding is connected across the armature. The resistance offered by the field is constant so the current is constant. … Therefore the speed of the DC shunt motor depends on the back EMF.

Is the speed of a DC shunt motor is increased the back emf of the motor will?

So, the back emf is directly proportional to speed. Hence, when the speed of a DC shunt motor is increased, then the back emf of the motor will increase.

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How is the speed of DC shunt motor related to its back emf and flux?

The speed of DC motor is directly proportional to back emf and inversely proportional to flux per pole. Since the flux is constant. Thereby the speed is only depends on the back emf and the speed isis proportional to the back emf. Hence speed is also increased by 5% with in increase 5% of back emf.

What is the back emf of DC shunt motor?

The back emf is developed in series with the applied voltage, but opposite in direction, i.e., the back emf opposes the current which causes it. Where Eb is the induced emf of the motor known as Back EMF, A is the number of parallel paths through the armature between the brushes of opposite polarity.

How is the speed of a DC shunt motor related to the armature current?

In dc shunt motor flux produced by field winding is proportional to field current. Here the input voltage is constant so field current and flux is also constant. So dc shunt motor is also called a constant flux or constant speed motor. Hence the speed of DC shunt motor is independent of armature current.

Why a DC series motor is always be started with load?

At the starting of the motor there is no back emf, so large current current flows cause high starting torque. This starting torque leads to very fast acceleration of motor if shaft is not connected to any load. This fast acceleration cause motor to damage. So series motor are always started with load.

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When the speed of DC motor is increased the speed of DC motor is increased?

(3) we can say, speed is inversely proportional to armature current. Thus, when the speed of the dc motor is increased, the armature current will decrease. So, the correct answer is “Option B”.

When the speed of a DC motor increases back emf?

Back emf is zero when the motor is not turning, and it increases proportionally to the motor’s angular velocity. Back emf is the generator output of a motor, and so it is proportional to the motor’s angular velocity ω.

Which the speed of DC motor is increased?

Consider separately excited DC motor. If field current is increased while armature terminal voltage is held constant then speed of motor will also increase.

What is the speed of DC motor related?

Hence, speed of a DC motor is directly proportional to emf of rotation (E) and inversely proportional to flux per pole (φ).

Does the speed of a shunt motor increase or decrease when the armature current increases?

The change in armature current and torque on supplying load is graphically shown below. This increase in the amount of torque increases the speed and thus compensating for the speed loss on loading. Thus the final speed characteristic of a DC shunt motor, looks like.

What is the relation between speed back emf and flux?

We know, back emf Eb of a DC motor is the induced emf in the armature conductors due to the rotation of armature in magnetic field. … This shows the speed of a dc motor is directly proportional to the back emf and inversely proportional to the fluxper pole.

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What does back emf depend on?

The back EMF depends, of course, on the speed of the motor — the change in magnetic flux that generates it increases with motor speed — so that as the motor begins to turn, the back EMF grows until the motor has reached its maximum speed, at which point the back EMF stays at its maximum value.

Why is back emf produced in DC motor?

When the armature of the DC motor rotates under the influence of driving torque, the armature of the conductors moves through a magnetic field inducing an emf in them. The induced emf is in the opposite direction to the applied voltage and is known as the back emf.

What is emf and back emf?

Counter-electromotive force (counter EMF, CEMF), also known as back electromotive force (back EMF), is the electromotive force (voltage) that opposes the change in current which induced it. CEMF is the EMF caused by magnetic induction (see Faraday’s law of induction, electromagnetic induction, Lenz’s law).